Cognitive models of depression in adults have been adapted for use with children, informing the assessment, prevention, and treatment of the illness in younger and younger age groups. Attributional theories of depression, such as the reformulated helplessness model (Abramson, Seligman, &Teasdale, 1978) and the hopelessness model (Abramson, Metalsky, &Alloy, 1989), are two of the more influential cognitive models of depression, influencing both research and intervention efforts. Both theories implicate cognitive variables (i.e., causal attributions about negative life events) in the etiology of depression. However, neither of these cognitive theories considers the role of cognitive development as they are applied depression in younger populations. In particular, attributional theories of depression do not consider that children's understanding of internality, stability, and globality may differ from that of adults. Developmental differences in how children understand these dimensions may change how attributional style and NLEs interact to predict depressive symptoms. This project has two main goals. The first is to continue to refine and validate a new measure, designed to assess the cognitive developmental prerequisites for an adult-like, depressive, attributional style. Knowing how and when children's understanding of internality/externality, stability/unstability, and globality/stability emerges will lead to the more developmental^ informed application of attributional models of depression in youth. I will use Item Response Theory to select items that discriminate between different levels of attributional understanding. I will also validate this measure against other cognitive and developmental measures. The second goal is to examine longitudinally how level of cognitive development moderates the relation of attributional style and negative life events to depression. Using data from children (8 to 15 years old) and their parents, we expect depressive symptoms to become more strongly related to attributional style as children develop a more adult-like understanding of key attributional dimensions. The assessment and treatment of depression in youth have been strongly influenced by cognitive models of depression that were originally developed and validated with adults. Child clinical methods can be made more effective as they are substantively and qualitatively adjusted in accordance with the child's changing level of cognitive development. By outlining developmental changes in children's healthy and depressive attributions, this research will pave the way for the construction of developmentally responsible assessments and interventions for depression in youth.